I found some news about the trailer for 'Horton Hears a Who'. I know this guy in Belgium who is a (how do you say it?) filmjournalist that gets some scoops sometimes.

He was talking about trailers that will premiere with new movies this summer. With Die Hard 4.0 comes the trailer for Death Sentence, a thriller with Kevin Bacon. The trailer for the next Pixar Wall•E (looks amazing btw!) will premiere with their Ratatouille. But most important, the trailer attached to The Simpsons Movie will be Horton Hears a Who! Yeah! You heard that one right!